• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.47-58
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• 2015

Four recycling scenarios involving pyroprocessing of spent fuel (SF) have been investigated for a 600-MWe transmutation sodium-cooled fast reactor (SFR), KALIMER. Performance evaluation was done with code system REBUS connected with TRANSX and TWODANT. Scenario Number 1 is the pyroprocessing of Canada deuterium uranium (CANDU) SF. Because the recycling of CANDU SF does not have any safety problems, the CANDU-Pyro-SFR system will be possible if the pyroprocessing capacity is large enough. Scenario Number 2 is a feasibility test of feed SF from a pressurized water reactor PWR. Thefsensitivity of cooling time before prior to pyro-processing was studied. As the cooling time sensitivity of cooling time before prior to pyro-processing was studied. As the cooling time increases, excess reactivity at the beginning of the equilibrium cycle (BOEC) decreases, thereby creating advantageous reactivity control and improving the transmutation performance of minor actinides. Scenario Number 3 is a case study for various levels of recovery factors of transuranic isotopes (TRUs). If long-lived fission products can be separated during pyroprocessing, the waste that is not recovered is classified as low- and intermediate-level waste, and it is sufficient to be disposed of in an underground site due to very low-heat-generation rate when the waste cooling time becomes >300 years at a TRU recovery factor of 99.9%. Scenario Number 4 is a case study for the recovery factor of rare earth (RE) isotopes. The RE isotope recovery factor should be lowered to ${\leq}20%$ in order to make sodium void reactivity less than <7$, which is the design limit of a metal fuel.

• Resources Recycling
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• v.33 no.4
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• pp.22-28
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• 2024

Waste PCBs contain a large amount of valuable resources, including copper, and technology to recover them is constantly being developed. Generally, to recycle waste PCBs, a physical pretreatment process such as shredding and crushing is required. However, during this stage, the loss rate of metals is high and the sorting efficiency is low, indicating a need for a more efficient recycling pretreatment process. In this study, a high-temperature milling process, which simultaneously employs heat treatment and ball milling, was utilized to efficiently recover copper from waste PCBs. An experiment was conducted at 350 ℃ with milling time, milling speed, and the weight of the balls as variables. The results showed a copper recovery rate of over 90% under the conditions of a ball weight of 500 g, a milling speed of 70 RPM, and a milling time of 5 hours. The purity of the recovered copper was approximately 93%, and through post-processing after the high-temperature milling process, the feasibility of reusing the recovered copper as a high-purity material was confirmed.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.553-556
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• 2009

This research aims at the recovery of valuable resource and more efficient waste treatment through solving the problem of pyrolysis technique. At first, in order to raise the economical efficiency, the low temperature pyrolysis experiment was carried out at the temperature of $450^{\circ}C$, which is lower than the common pyrolysis temperature area ($500{\sim}1000^{\circ}C$). We could lower the reaction temperature and reduce the reaction time by using catalyst. Also we used indirect heat for the purpose of maintaining favorable anoxic condition. As a result, we could raise the recovery rate of the valuable copper and synthetic fuel oil. Furthermore, the by-products and flue gas could be treated more effectively as well. The flue gas passed through two stage neutralization tank, so that dioxin hardly occurs and other environment items are controlled fairly well to the environmental standard. Throughout this study, we produced the low temperature pyrolysis equipment (GTPK-001) as mentioned above, and we found out that the technique can be commercialized economically as well as environmentally friendly.

• Advances in Energy Research
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• v.3 no.3
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• pp.167-179
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• 2015

This paper presents a techno-economic analysis of a partial repowering scheme for an existing 210 MW coal fired power plant by integrating a gas turbine and by employing waste heat recovery. In this repowering scheme, one of the four operating coal mills is taken out and a new natural gas fired gas turbine (GT) block is considered to be integrated, whose exhaust is fed to the furnace of the existing boiler. Feedwater heating is proposed through the utilization of waste heat of the boiler exhaust gas. From the thermodynamic analysis it is seen that the proposed repowering scheme helps to increase the plant capacity by about 28% and the overall efficiency by 27%. It also results in 21% reduction in the plant heat rate and 29% reduction in the specific $CO_2$ emissions. The economic analysis reveals that the partial repowering scheme is cost effective resulting in a reduction of the unit cost of electricity (UCOE) by 8.4%. The economic analysis further shows that the UCOE of the repowered plant is lower than that of a new green-field power plant of similar capacity.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.191-194
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• 2011

Low-grade waste heat has generally been discarded in industry due to lack of efficient recovery methods. In recent years, organic Rankine cycle(ORC) has become a field of intense research and appears as a promising technology for conversion of heat into useful work of electricity. In this work thermodynamic performance of ORC with superheating of vapor is comparatively assessed for various working fluids. Special attention is paid to the effects of system parameters such as the evaporating temperature on the characteristics of the system such as maximum possible work extraction from the given source, volumetric flow rate per 1 kW of net work and quality of the working fluid at turbine exit as well as thermal efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.30-35
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• 2021

The present study examined the effects of various guide fin structures and boundary parameters on the thermal performance of heat exchangers used in heat recovery thermoelectric generators. The heat transfer rate and pressure drop of the heat exchangers without fins, with circular fins, with triangular fins, and with combined circular and triangular fins were simulated numerically using ANSYS 19.1 commercial code to confirm the effect of the guide fin structures. The heat transfer rate of the heat exchanger with combined fins was 27.0%, 5.2%, and 1.5% higher than those without fins, with circular fins, and with triangular fins, respectively. The pressure drop characteristic of the heat exchanger with the combined fins was 28.3% higher than that without fins but 9.2% and 10.5% lower than those with circular fins and with triangular fins, respectively. The heat exchanger with combined fins as the optimal model showed the highest heat transfer rate of 5664.9 W and pressure drop of 1454.02 Pa for highest hot gas temperature, maximum flow rates of hot gas and coolant, and lowest coolant temperature.

• Clean Technology
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• v.30 no.1
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• pp.28-36
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• 2024

As demand for electric vehicles increases, the market for lithium-ion batteries is also rapidly increasing. The battery life of lithium-ion batteries is limited, so waste lithium-ion batteries are inevitably generated. Accordingly, lithium was selectively preleached from waste lithium iron phosphate (LiFePO₄, hereafter referred to as the LFP) cathode material powder among lithium ion batteries, and iron phosphate (FePO₄) powder was recovered. The recovered iron phosphate powder was mixed with alkaline sodium carbonate (Na₂CO₃) powder and heat treated to confirm its crystalline phase. The heat treatment temperature was set as a variable, and then the leaching rate and powder characteristics of each ingredient were compared after water leaching using Di-water. In this study, lithium showed a leaching rate of approximately 100%, and in the case of powder heat-treated at 800 ℃, phosphorus was leached by approximately 99%, and the leaching residue was confirmed to be a single crystal phase of Fe₂O₃. Therefore, in this study, lithium, phosphorus, and iron components were individually separated and recovered from waste LFP powder.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.307-312
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• 2023

In this study, a catalytic oxidation-heat recovery system was designed that can remove unreacted with a concentration of about 1% to 6% in the exhaust gas of hydrogen fuel cells and recover heat to ensure safety in the hydrogen economy. The safety system was devised by filling hydrogen oxidation catalysts at room temperature that can remove unreacted hydrogen without any energy source, and an exhaust-heat recovery device was integrated to efficiently recover the heat released from the oxidation reaction. Through CFD analysis, variations in pressure and fluid within the system were shown depending on the filling conditions of the hydrogen oxidation system. In addition, it was found that waste heat could be recovered by optimizing the temperature of the exhaust gas, flow rate, and pressure conditions within the heat recovery system and securing hot water above 40 ℃ by utilizing the exhaust gas oxidation heat source above 300 ℃. Through this study, it was possible to confirm the potential of utilizing hydrogen processes, which are applied in small to medium-sized systems such as hydrogen fuel cells, as a safety system by evaluating them at a pilot scale. Additionally, it could be a safety guideline for responding to unexpected hydrogen safety accidents through further pilot-scale studies.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.565-570
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• 2001

Annually, Taiwan generates approximately 2 million tons of inorganic wastes in the form of sludge, fly ash and slug. To increase the added value of waste and maintain the increasingly insufficient supply of natural gravel, large public construction projects account for this large demand each year. future architectural trends are leading towards high-rise buildings. In light of the above, Center for Environmental, Safety and Health Technology Development, Industrial Technology Research Institute has developed the technology of manufacturing cold-bonding, sintering and bloating types of lightweight aggregates with a specific gravity ranging between 0.7~1.7, water absorption rate < 30%. The lightweight aggregate verified by physical property tests can be used as a substitute for the natural aggregate, which generally appears in replacing gravel in concrete, soundproofing and heat insulation materials. Doing so would not only moderate waste disposal problems, but also achieve the goal of resource recovery.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.52-57
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• 2018

Most current ships have adopted on-board diesel generators to produce electricity, but the overall efficiency of equipment is down to about 50% due to thermal losses from operations such as exhaust gas, jacket water cooler, scavenge air cooler, etc. Recently, fuel cells have been highlighted as a promising technology to reduce the effect on the environment and have a higher efficiency. Therefore, this paper suggested a solid oxide fuel cell (SOFC)-gas turbine (GT) using waste heat from a SOFC and SOFC-GT-steam turbine (ST) with Rankine cycle. To compare both configurations, the fuel flow rate, current density, cell voltage, electrical power, and overall efficiency were evaluated at different operating loads. The overall efficiency of both SOFC hybrid systems was higher than the conventional system.